Field of the Invention
Embodiments of the present disclosure generally relate to power systems and, more particularly, to a method and apparatus for determining a corrected monitoring voltage.
Description of the Related Art
Solar panels have historically been deployed in mostly remote applications, such as remote cabins in the wilderness or satellites, where commercial power was not available. Due to the high cost of installation, solar panels were not an economical choice for generating power unless no other power options were available. However, the worldwide growth of energy demand is leading to a durable increase in energy cost. In addition, it is now well established that the fossil energy reserves currently being used to generate electricity are rapidly being depleted. These growing impediments to conventional commercial power generation make solar panels a more attractive option to pursue.
Solar panels, or photovoltaic (PV) modules, convert energy from sunlight received into direct current (DC). The PV modules cannot store the electrical energy they produce, so the energy must either be dispersed to an energy storage system, such as a battery or pumped hydroelectricity storage, or dispersed by a load. One option to use the energy produced is to employ one or more inverters to convert the DC current into an alternating current (AC) and couple the AC current to the commercial power grid. The power produced by such a distributed generation (DG) system can then be sold to the commercial power company.
In order to mitigate potential safety hazards, a DG coupled to a commercial power grid must be operated in accordance with relevant regulatory requirements, such as IEEE-1547. As part of meeting the IEEE-1547 requirements, an inverter within a DG must be deactivated under certain circumstances, including line frequency or line voltage operating outside of pre-defined limits. The IEEE-1547 standard specifies that such voltage requirements must be met at a Point of Common Coupling (PCC) between the commercial power system and the DG (i.e., a point of demarcation between the public utility service and the DG).
For installations where an inverter within a DG is located a significant distance from the PCC, an output voltage measured at the inverter may be higher than a voltage measured at the PCC due a voltage drop along the line from the inverter to the PCC. In some circumstances, the measured voltage at the inverter may exceed the required voltage range although the voltage at the PCC remains within the required range, resulting in the inverter unnecessarily shutting down and thereby reducing energy production. Additionally, as the inverter ceases power production and the voltage at the inverter is reduced to acceptable levels, the inverter once again activates and begins producing power, resulting in a continued oscillation that negatively impacts power production.
Therefore, there is a need for a method and apparatus for correcting a monitoring voltage measured at an inverter.